Airborne warning radars are oftentimes deployed not only on all kinds of manned military aircraft but also on unmanned aerial vehicles to be able to detect radar targets.
When such radars overfly urban environments there are numbers of RF emitters that do not constitute threats but on which the radar will falsely declare target detections.
The threat environment today, especially in the urban environment, is becoming more dense, with the cost of reacting to false alarms becoming problematic.
To date, airborne radars have not been provided with a mechanism of monitoring the RF environment to prevent such false alarms.
In a typical radar action one illuminates the environment by projecting pulses to pick up returns and decide whether or not the returns correspond to a real target or threat. The problem in accurately detecting these targets without false detections is complicated by the presence of RF interference from external RF sources.
Due to today's increased RF environment, there are both in-band signals that result in unacceptable false alarms, as well as out-of-band signals from higher-powered RF emitters. In a typical urban environment there may be four to five such RF emitters that operate outside of the frequency range of the airborne radar. Out-of-band RF emitters that are within close range proximity to the airborne radar can actually gate the returned pulses by overloading the airborne receiver. This saturation of the airborne receiver causes amplitude modulation on its radar return signal and generally results in false alarms.